I've just replaced the battery on my 1800 K. It lives in a garage on a conditioning charger. It came with a Banner and I'd previously changed that for a Powervamp PVR 25, with which I was very happy. This time round the big decision was whether to switch to a lithium battery. Lots in the archives on this but I'm mean and risk averse. I bought a PVR Clubsport NP from their eBay store. NB: Terminals might be different from your current, but they sell adaptors. Case size might be different but you can fettle the straps or buy the appropriate case. I had to lengthen one fat red wire.Jonathan